(function(global, factory) {
	if(typeof define === 'function' && define.amd) {
		define([], factory);
	} else if(typeof module !== 'undefined' && module.exports) {
		module.exports = factory();
	} else {
		global.ReconnectingWebSocket = factory();
	}
})(this, function() {

	if(!('WebSocket' in window)) {
		return;
	}

	function ReconnectingWebSocket(url, protocols, options) {

		// Default settings
		var settings = {

			/** Whether this instance should log debug messages. */
			debug: false,

			/** Whether or not the websocket should attempt to connect immediately upon instantiation. */
			automaticOpen: true,

			/** The number of milliseconds to delay before attempting to reconnect. */
			reconnectInterval: 1000,
			/** The maximum number of milliseconds to delay a reconnection attempt. */
			maxReconnectInterval: 30000,
			/** The rate of increase of the reconnect delay. Allows reconnect attempts to back off when problems persist. */
			reconnectDecay: 1.5,

			/** The maximum time in milliseconds to wait for a connection to succeed before closing and retrying. */
			timeoutInterval: 2000,

			/** The maximum number of reconnection attempts to make. Unlimited if null. */
			maxReconnectAttempts: null,

			/** The binary type, possible values 'blob' or 'arraybuffer', default 'blob'. */
			binaryType: 'blob'
		}
		if(!options) {
			options = {};
		}

		// Overwrite and define settings with options if they exist.
		for(var key in settings) {
			if(typeof options[key] !== 'undefined') {
				this[key] = options[key];
			} else {
				this[key] = settings[key];
			}
		}

		// These should be treated as read-only properties

		/** The URL as resolved by the constructor. This is always an absolute URL. Read only. */
		this.url = url;

		/** The number of attempted reconnects since starting, or the last successful connection. Read only. */
		this.reconnectAttempts = 0;

		/**
		 * The current state of the connection.
		 * Can be one of: WebSocket.CONNECTING, WebSocket.OPEN, WebSocket.CLOSING, WebSocket.CLOSED
		 * Read only.
		 */
		this.readyState = WebSocket.CONNECTING;

		/**
		 * A string indicating the name of the sub-protocol the server selected; this will be one of
		 * the strings specified in the protocols parameter when creating the WebSocket object.
		 * Read only.
		 */
		this.protocol = null;

		// Private state variables

		var self = this;
		var ws;
		var forcedClose = false;
		var timedOut = false;
		var eventTarget = document.createElement('div');

		// Wire up "on*" properties as event handlers

		eventTarget.addEventListener('open', function(event) {
			self.onopen(event);
		});
		eventTarget.addEventListener('close', function(event) {
			self.onclose(event);
		});
		eventTarget.addEventListener('connecting', function(event) {
			self.onconnecting(event);
		});
		eventTarget.addEventListener('message', function(event) {
			self.onmessage(event);
		});
		eventTarget.addEventListener('error', function(event) {
			self.onerror(event);
		});

		// Expose the API required by EventTarget

		this.addEventListener = eventTarget.addEventListener.bind(eventTarget);
		this.removeEventListener = eventTarget.removeEventListener.bind(eventTarget);
		this.dispatchEvent = eventTarget.dispatchEvent.bind(eventTarget);

		/**
		 * This function generates an event that is compatible with standard
		 * compliant browsers and IE9 - IE11
		 *
		 * This will prevent the error:
		 * Object doesn't support this action
		 *
		 * http://stackoverflow.com/questions/19345392/why-arent-my-parameters-getting-passed-through-to-a-dispatched-event/19345563#19345563
		 * @param s String The name that the event should use
		 * @param args Object an optional object that the event will use
		 */
		function generateEvent(s, args) {
			var evt = document.createEvent("CustomEvent");
			evt.initCustomEvent(s, false, false, args);
			return evt;
		};

		this.open = function(reconnectAttempt) {
			ws = new WebSocket(self.url, protocols || []);
			ws.binaryType = this.binaryType;

			if(reconnectAttempt) {
				if(this.maxReconnectAttempts && this.reconnectAttempts > this.maxReconnectAttempts) {
					return;
				}
			} else {
				eventTarget.dispatchEvent(generateEvent('connecting'));
				this.reconnectAttempts = 0;
			}

			if(self.debug || ReconnectingWebSocket.debugAll) {
				console.debug('ReconnectingWebSocket', 'attempt-connect', self.url);
			}

			var localWs = ws;
			var timeout = setTimeout(function() {
				if(self.debug || ReconnectingWebSocket.debugAll) {
					console.debug('ReconnectingWebSocket', 'connection-timeout', self.url);
				}
				timedOut = true;
				localWs.close();
				timedOut = false;
			}, self.timeoutInterval);

			ws.onopen = function(event) {
				clearTimeout(timeout);
				if(self.debug || ReconnectingWebSocket.debugAll) {
					console.debug('ReconnectingWebSocket', 'onopen', self.url);
				}
				self.protocol = ws.protocol;
				self.readyState = WebSocket.OPEN;
				self.reconnectAttempts = 0;
				var e = generateEvent('open');
				e.isReconnect = reconnectAttempt;
				reconnectAttempt = false;
				eventTarget.dispatchEvent(e);
			};

			ws.onclose = function(event) {
				clearTimeout(timeout);
				ws = null;
				if(forcedClose) {
					self.readyState = WebSocket.CLOSED;
					eventTarget.dispatchEvent(generateEvent('close'));
				} else {
					self.readyState = WebSocket.CONNECTING;
					var e = generateEvent('connecting');
					e.code = event.code;
					e.reason = event.reason;
					e.wasClean = event.wasClean;
					eventTarget.dispatchEvent(e);
					if(!reconnectAttempt && !timedOut) {
						if(self.debug || ReconnectingWebSocket.debugAll) {
							console.debug('ReconnectingWebSocket', 'onclose', self.url);
						}
						eventTarget.dispatchEvent(generateEvent('close'));
					}

					var timeout = self.reconnectInterval * Math.pow(self.reconnectDecay, self.reconnectAttempts);
					setTimeout(function() {
						self.reconnectAttempts++;
						self.open(true);
					}, timeout > self.maxReconnectInterval ? self.maxReconnectInterval : timeout);
				}
			};
			ws.onmessage = function(event) {
				if(self.debug || ReconnectingWebSocket.debugAll) {
					console.debug('ReconnectingWebSocket', 'onmessage', self.url, event.data);
				}
				var e = generateEvent('message');
				e.data = event.data;
				eventTarget.dispatchEvent(e);
			};
			ws.onerror = function(event) {
				if(self.debug || ReconnectingWebSocket.debugAll) {
					console.debug('ReconnectingWebSocket', 'onerror', self.url, event);
				}
				eventTarget.dispatchEvent(generateEvent('error'));
			};
		}

		// Whether or not to create a websocket upon instantiation
		if(this.automaticOpen == true) {
			this.open(false);
		}

		/**
		 * Transmits data to the server over the WebSocket connection.
		 *
		 * @param data a text string, ArrayBuffer or Blob to send to the server.
		 */
		this.send = function(data) {
			if(ws) {
				if(self.debug || ReconnectingWebSocket.debugAll) {
					console.debug('ReconnectingWebSocket', 'send', self.url, data);
				}
				return ws.send(data);
			} else {
				throw 'INVALID_STATE_ERR : Pausing to reconnect websocket';
			}
		};

		/**
		 * Closes the WebSocket connection or connection attempt, if any.
		 * If the connection is already CLOSED, this method does nothing.
		 */
		this.close = function(code, reason) {
			// Default CLOSE_NORMAL code
			if(typeof code == 'undefined') {
				code = 1000;
			}
			forcedClose = true;
			if(ws) {
				ws.close(code, reason);
			}
		};

		/**
		 * Additional public API method to refresh the connection if still open (close, re-open).
		 * For example, if the app suspects bad data / missed heart beats, it can try to refresh.
		 */
		this.refresh = function() {
			if(ws) {
				ws.close();
			}
		};
	}

	/**
	 * An event listener to be called when the WebSocket connection's readyState changes to OPEN;
	 * this indicates that the connection is ready to send and receive data.
	 */
	ReconnectingWebSocket.prototype.onopen = function(event) {};
	/** An event listener to be called when the WebSocket connection's readyState changes to CLOSED. */
	ReconnectingWebSocket.prototype.onclose = function(event) {};
	/** An event listener to be called when a connection begins being attempted. */
	ReconnectingWebSocket.prototype.onconnecting = function(event) {};
	/** An event listener to be called when a message is received from the server. */
	ReconnectingWebSocket.prototype.onmessage = function(event) {};
	/** An event listener to be called when an error occurs. */
	ReconnectingWebSocket.prototype.onerror = function(event) {};

	/**
	 * Whether all instances of ReconnectingWebSocket should log debug messages.
	 * Setting this to true is the equivalent of setting all instances of ReconnectingWebSocket.debug to true.
	 */
	ReconnectingWebSocket.debugAll = false;

	ReconnectingWebSocket.CONNECTING = WebSocket.CONNECTING;
	ReconnectingWebSocket.OPEN = WebSocket.OPEN;
	ReconnectingWebSocket.CLOSING = WebSocket.CLOSING;
	ReconnectingWebSocket.CLOSED = WebSocket.CLOSED;

	return ReconnectingWebSocket;
});